I follow this advice with one small modification. Namely, mine goes:

    - Make it once.  
    - Make it right.  
    - Make it fast.  

"Make it right" as the first step can trick an unseasoned developer into never finishing a prototype. I don't mind the first iteration of something being sloppy and then pursuing correctness with an existing solution to the problem in hand.

I'm curious if you've got a sense of the interplay between prototyping and correctness similar to your sense of the interplay between performance tuning and correctness? Any thoughts?